My girlfriend owns a 2010 Volkswagen Polo (MK VI) 1.2 3-door bought and maintained by a franchised Volkswagen dealer from new. Upon returning to the vehicle after it had rained for the entire day, we discovered the roof lining was very damp and had soaked through from the front to rear passenger side. It does not seem to have leaked into any foot wells however.

The car has never had this problem before and there is no sunroof or roof bars for water to leak through from. Likewise, the roof run off channels are clear and cannot be blocked and all the windows and doors were securely closed. It appears to be getting worse with continued exposure to rain.

Do you have any ideas as to what the source of the problem may be?